Abdullah bin Abdullah bin Umar narrates from his father (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When the water amounts to two qullahs (large jars), it does not carry impurity (that is, it does not become impure)."
Imam al-Daraqutni (may Allah have mercy on him) says regarding these two narrations: Since there is disagreement over Abu Usamah in the chain, we wished to know which is correct. On examination, it became clear that Shu'ayb bin Ayyub narrated it from Abu Usamah, from al-Walid bin Kathir, in both ways; so both versions are authentically established from Abu Usamah. Al-Walid bin Kathir also narrates it from both of them. Abu Usamah sometimes narrates it as al-Walid bin Kathir from Muhammad bin Ja'far bin al-Zubayr, and sometimes as al-Walid from Muhammad bin Abbad bin Ja'far. And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1232